Open-box type dc solenoid

ABSTRACT

AN OPEN-BOX TYPE DC SOLENOID, IN WHICH A BOBBIN MOUNTED WITH A COIL AND TAKEN INTO A U-SHAPED FRAME FROM ITS OPEN SIDE IS PRESSEDLY SUPPORTED BY A PAIR OF RINGED SPACERS EACH INSERTED IN THE SPACE BETWEEN THE BOBBIN AND EITHER ONE OF THE UPRIGHT SIDEWALLS OF THE FRAME. A STOPPER WHICH IS INSERTED INSIDE THE TUBULAR HOLE OF THE BOBBIN TO POSITION THE INNER END OF A PLUNGER NEAR TO THE MIDDLE OF THE AXIAL LENGTH OF THE COIL IS ONLY CAULKED AT ITS OUTER END TO THE FRAME TO FIX ITS POSITION, WHILE OTHER COMPONENTS ARE FIXEDLY SUPPORTED BY EACH OTHER WITHOUT CAULKING. ONE OF THE SPACERS IS MOUNTED ON THE STOPPER AND THE OTHER IS MOUNTED ON A FLANGE EXTENDING OUTWARDLY COAXIALLY FROM THE BOBBIN OR A PLUNGER GUIDE INSERTED INTO THE BOBBIN, THE LATTER SPACER HAVING RELATIVELY HIGH MAGNETIC PERMEABILITY AND CONCENTRATING OR CONVERGING MAGNETIC FLUX AROUND THE PLUNGER.

United States Patent Inventor Katutosi Higuma Tokyo, Japan Appl. No. 879,704 Filed Nov. 25, 1969 Patented June 28, 1971 Assignee KabnshlkLKaisha Chnkyo Gijutsu Center Tokyo, Japan Priority Apr. 19,1969

Japan 44/35888 OPEN-BOX TYPE DC SOLENOID 2 Claims, 8 Drawing Figs. [1.8. CI. 335/255, 335/262, 335/278 Int. Cl 1101: 7/08 Field otSearch 335/255, 258, 262, 278

References Cited UNITED STATES PATENTS 2,176,564 10/1939 Stumpf 335/262X 1 13,sss,770

Primary Examiner-G. Harris Attorney-Browdy and Neimark ABSTRACT: An open-box type DC solenoid, in which a bobbin mounted with a coil and taken into a U-shaped frame from its open side is pressedly supported by a pair of ringed spacers each inserted in the space between the bobbin and either one of the upright sidewalls of the frame. A stopper which is inserted inside the tubular hole of the bobbin to position the inner end of a plunger near to the middle of the axial length of the coil is only caulked at its outer end to the frame to fix its position, while other components are fixedly supported by each other without caulking. One of the spacers is mounted on the stopper and the other is mounted on a flange extending outwardly coaxially from the bobbin or a plunger guide inserted into the bobbin, the latter spacer having relatively high magnetic permeability and concentrating or converging magnetic flux around the plunger.

Patented June 28, 1971 3,588,170

3 Sheets-Shoot 1 F] G L PRIOR ART 9 fur- 2 F165 PRIOR ART FIG.6 PRIQR ART INVENTOR BY MW ATTORNEY Patented June 28, 1971 3,588,770

3 Sheets-Sheet 2 Pull-in character of conventional type W. of prsent invention '0 E T 5 IOOOAT O 0 2 012 v 80OAT o I l l STroKe (mm) INVENTOR ATTORNEY ('3) Jemod ugn 3 Shoots-Shoot I ull-in character with a spacer of low magnetic permeability with a spacer of vhigh magnetic permeability Strok e m m) F I G. 8

INVENTOR M'nd/ 1 OPEN-BOX TYPE DC SOLENOID This invention relates to an open-box type DC solenoid.

An object of the present invention is to provide an open-box type DC solenoid having much simpler constructions-as compared to a conventional solenoid of the type and easily assembled.

Another object of the present invention is to provide an open-box type DC solenoid having a good pull-in character not withstanding its construction that a field coil is mounted into a U-shaped frame having an opening side which extends in parallel with a plunger placed in the solenoid coaxially with the field coil and remains open.

For further comprehension of the invention, and of the objects and advantages thereof, reference will be had to the following description and accompanying drawing, and to the appended claims in which the various novel features of the invention are more particularly set forth.

In the accompanying drawing forming a material part of this disclosure:

FIG. 1 is a side elevational view of a solenoid formed in accordance with the invention, the upper part being broken away.

FIG. 2 is a left side view of FIG. 1.

FIG. 3 is a bottom plan view of FIG. 1.

FIG. 4 is a side elevational view of a conventional solenoid, the lower part being broken away.

FIG. 5 is a right side view of FIG. 4.

FIG. 6 is a bottom plan view of FIG. 4.

FIG. 7 is a diagram showing pull-in characters of the present invention solenoid and a conventional solenoid at different ampere-turns.

FIG. 8 is a diagram showing pull-in characters of solenoids formed with or without a magnetism-increasing spacer in accordance with the present invention.

In a conventional box-type DC solenoid, as shown in FIGS. 4, 5 and 6, a stopper 3 which normally positions the inner end of a plunger 2 near the middle of the axial length of a coil 6, is fitted to a U-shaped frame 1 having an open side which extends transversely to the axial direction of the stopper 3 or plunger 2, by introducing it inside the frame through the opening side, insertedly fitting one of its ends which does not come into abutment with the inner end of the plunger, into a hole perforated at a sidewall la which is opposite to the opening side and caulking the end to the sidewall la at positions 30.

A plunger guide 4 made of a metallic pipe having an inner circumferential wall, the diameter of which is substantially equal to or slightly larger than that of the stopper 3, is pressedly fitted onto the stopper 3. Next, the coil 6 wound on a core 5 is mounted onto the plunger guide 4 from the open side of the frame I. A cover plate 7 with a spacer 9 is set onto the open side of the frame 1 to form a closed yoke. The cover plate 7 and spacer 9 have respectively a central hole 7b having a dia...eter substantially equal to that of the plunger guide 4 and an upper and lower projection 7a and 7a which can be insertedly fitted into an upper and lower cut out portion 8 and 8 of the frame 1. The cover plate and spacer are fitted to the frame 1 by caulking the edges of said portions 8 and 8 to the projections 7a and 7a. The plunger 2 is inserted into the plunger guide 4, extending one of its ends outwardly from the cover plate 7.

It should be noted that in a conventional solenoid as above, several steps are required to assembly it. To wit, a step for caulking the stopper 3 of the plunger 2 to the frame 1; a step for fitting the end of the plunger guide 4 onto the stopper 3; a step for insertedly fitting the coil 6 onto the plunger guide 4; and a step for fitting the cover plate 7 to the frame 1.

Compared to conventional DC solenoids which need a number of steps in its assembly, as mentioned above, the assembly of the DC solenoid in accordance with this invention is much simpler, wherein a cover plate which closes an open side of a U-shaped frame to form a continued yoke and prevent magnetic flux from diffusing is eliminated, nevertheless its pull-in character is not inadversely affected by incorporating a magnetism increasing spacer thereinto.

As shown in FIGS. 1, 2 and- 3, in the present invention, a frame 10 is formed in a U-shape in a side elevational view having its open side extending in parallel with the axial direction of a coil 11. A tubular bobbin 12 mounted thereon with said coil 11 and slideably carrying a magnetism-increasing spacer 13 on a flange 12a outwardly coaxially extending therefrom is taken into the frame 10 from its open side. The outer end of the flange 12a is insertedly fitted into a hole 14 provided centrally to one of the upright sidewall 10a of the frame 10, by sliding the magnetism-increasing spacer 13 towards the bobbin 12 until it is pressed between the inner wall of upright sidewall 10a and the bobbin. The magnetism-increasing spacer has such a thickness that it can position the coil 11 to the middle between the upright sidewall 10a and another upright sidewall 10b. A coil-fixing spacer 15 having a central hole is then inserted into a space between the sidewall 10b and the bobbin 12, a stopper 16 which normally positions the inner end of a plunger 19 near at the middle of the axial length of the coil 11 is inserted into the tubular hole of the bobbin 12 through the hole 14 from the outside of the said sidewall 10a until its forward end 18 protrudes from a hole 17 centrally provided .to the sidewall 10b, said forward end 18 is caulked to I the sidewall 10b, and finally the plunger 19 is inserted into the tubular hole of the bobbin 12 from the direction of the sidewall 10a to complete a solenoid.

As shown in FIG. 7, the open-box type DC solenoid constructed in accordance with the invention has shown almost the same pull-in character as the conventional box-type DC solenoid has.

It is considered that the magnetism-increasing spacer 13 serves to concentrate or converge the magnetic flux around the plunger 19 rather than diffusing it over the frame 10 through its open side. The pull-in character of the present invention solenoid is consequently increased. While said spacer 13 is preferably made of soft magnetic material with relatively high magnetic permeability, the spacer 15 may be of a material with low magnetic permeability such as resins, since the inventor has not found any noticeable difference between the one having high magnetic permeability and the another having no magnetic permeability, in view of increasing magnetism working on the plunger.

In the embodiment shown in FIG. 1, the bobbin 12 serves to carry thereon a coil 11 and also to guide the axial movement of the plunger 19, whereas an independent plunger guide may be employed, inside of which the plunger 19 can slidably move along it axial direction and over which the bobbin l2 and spacer 13 can be mounted.

It should be noted that in the solenoid according to the invention as above, the weight of the frame 10 is considerably reduced, and only few steps are required to assemble it. To wit, a step for mounting the magnetism-increasing spacer 13 onto the flange 12a of the bobbin 12 with the coil 11; a step for taking said bobbin 12 into the frame 10 from its open side and insertedly engaging the flange 12a to the hole of the upright sidewall 1011, while pressing the spacer 13 towards the bobbin; a step for inserting the spacer 15 between the bobbin and the other upright sidewall 10b to fixedly support the bobbin in the frame; a step for inserting the stopper 16 into the tubular hole of the bobbin and caulking its forward end 18 to the wall 10b; and a step for inserting the plunger 19 into the tubular hole of the bobbin; wherein a caulking step is only required to fix the forward end 18 of the stopper 16 to the wall 10b of the frame.

While a preferred embodiment of the invention has been illustrated and described, it is to be understood that the invention shall not be limited to the precise constructions herein disclosed and the right is reserved to all changes and modifications coming within the scope of the invention as defined in the appended claims.

Iclaim:

1. An open-box type DC solenoid comprising a frame of a U-shape in its side elevational view having a pair of upright sidewalls projecting at a right angle from a bottom wall and each provided centrally with a hole and an open side extending between the upper. free edges of the upright sidewalls in parallel with a plunger, a bobbin mounted with a coil and supported between the upright sidewalls with its tubular hole coaxial with the holes of said upright sidewalls by a pair of spacers each having a central hole and insertedly fitted between the bobbin and either one of the upright sidewalls, at least one of said spacers being of a soft magnetic material with relatively high magnetic permeability, a stopper extending inside the tubular hole of the bobbin and having an outer end projected through the hole of one of the spacers to one of the upright sidewalls and caulked to said wall and an inner end projected near to the middle of the tubular hole of the bobbin,

and the aforementioned plunger slideably mounted inside the tubular hole of the bobbin and having one end normally con- 

